I often use TC plugins, but I'm generally not impressed by their audio quality. However, they are easy to use with good enough sounding results. Kinda like Waves. I often use Fabrik C Studio compressor/deesser/limiter/EQ and Fabrik R Studio reverb, but not Assimilator. For the purpose of copying and applying the frequency response of some other mix I would still use Voxengo CurveEQ.

But I must say that I found it rather useless. It sounds better to just use a good quality EQ, speakers, and your ears to make a mix sound better, because what works for that mix you like, usually doesn't not work for yours.

I've used it some years ago. It's a good tool to see your mistakes, and to point the direction you have to take your mix to (it's not magic, so it won't make you instantly sounds like your favorite record...whatever maketing says...). To me, it's kind of a "enhanced" reference track to point "goods and wrongs" when comparing the original and the processed mix.

There are some other options, like the "match EQ" option in Ozone's equalizer, or the old BIAS RepliQ (only 32bit if i remember correctly).
There's also the Alliance DSM, which is quite a good matching plugin in term of results, but a little different beast as it works on multiband dynamics (opposed as the static eq for the other ones that i mentionned). Worth giving a try IMHO.

As for any tool, it won't make a poor mix sounds great, but it sure can help when you're a little lost, or when your hears are too much used to your own mix, and no more able to critically listen to it.